E–T phase diagram of the 6.5/65/35 PLZT incipient ferroelectric

The electric-field–temperature (E–T) phase diagram for lanthanum modified lead zirconate (PLZT) 6.5/65/35 hot-pressed ceramics was determined by measurements of the quasistatic field-cooled–field-heated (FC/FH) dielectric susceptibilities. Approximately linear dependence of the phase transition line between the ergodic relaxor and ferroelectric phases on the bias electric field was found. In zero electric bias field the incipient ferroelectricity is established at nonzero phase transition temperatures. From the field-cooled polarization measurements a quasistatic spontaneous polarization of 0.37 As/m2 was determined at 25 °C. Measurement of the frequency dependent, linear complex dielectric constant as a function of the bias electric field shows a significant change in its temperature dependence as well as in the temperature dependence of the characteristic relaxation time, indicating freezing of those sample regions dominated by the disordered nanocluster relaxor state, to the nonergodic glass-like relaxor state.